This invention relates to the surface treatment of polymeric materials for the purpose of bonding or grafting chemical substances to the surface thereof. It relates particularly to silicone rubbers and to bonding to silicone rubbers substances having a desired biological activity or compatibility when implanted in the human body.
Many different techniques have been used to modify material surfaces in order to improve their resistance to thrombosis, infection and inflammation. Techniques for surface modification can include physicochemical methods such as the physical deposition of a coating on the material surface, chemical modification of the material surface, graft polymerization onto the material surface and plasma gas discharge. For example, in U.S. Pat. No. 4,613,517 issued to Williams et al., a method for heparin attachment to a polymeric surface is disclosed. The polymeric surface is activated by a plasma, steeped in a cationic surface active agent and reacted with heparin. Also, for example, in U.S. Pat. No. 5,080,924 issued to Kamel et al., biocompatible, surface modified material is produced by covalently grafting a biocompatible material having pendant carboxyl or amine groups to a substrate material in the presence of a radio frequency plasma. Or, for example, in U.S. Pat. No. 3,955,012 issued to Okamura et al., silicone rubber articles are subjected to a spark discharge, coated with collagen and subjected to ionizing radiation in a moist atmosphere to produce a surface of improved biocompatibility. Since silicone rubbers have a well established history of use in medical implants such as in heart pacemaker leads, implantable prosthetic devices and the like, it would be especially desirable to be able to provide surface modifications to silicone rubber that would extend and enhance its usefulness in various implantable devices. However, silicone rubber ha& heretofore proved to be a difficult surface to bond to, producing poor yields of biomaterial adhered to the surface.
It is therefore an object of the present invention to provide a modified silicone rubber surface to which a wide variety of materials may be readily be bonded.
It is also an object of the present invention to provide a modified silicone rubber surface to which materials may be bonded with a high yield of material on the surface.